Some electrical systems include controllers that control operations of other devices. Some of these systems can be lighting systems having a controller that communicates with light sources for controlling which light sources are activated or deactivated. The systems may include separate pathways or wires for supplying current to the light sources for powering the light sources and communicating with the light sources. One example of such a system is a digitally addressable lighting interface (DALI) system. The DALI system may include a controller that controls operation of light drivers to control corresponding light sources. The drivers may be powered from an electrical grid (e.g., an alternating current grid, such as a utility grid). The controller can control operation of the light drivers by communicating control signals over a control bus. The control bus and the voltage lines (through which current is supplied from the grid to power the drivers) are separate pathways. As a result, the power consumption of the drivers and light sources from the grid does not have an impact on the load on the control bus.
If a DALI system is to include one or more devices that cannot be powered by an electrical grid or another separate, external power source, these devices may need to be powered by the control bus of the DALI system. But, because the control bus may be limited in the amount of power it can supply (e.g., 250 milliamps or less of turnover current), the amount of current that can be supplied to the devices is limited. As a result, the number of these devices that can be included in the DALI system may be limited (e.g., to two devices or less), or the devices may only be able to operate on very limited amounts of power from the DALI control bus.
Consequently, devices such as incandescent light sources, light sources having tungsten filaments, or other devices (e.g., other than light sources) may not be connected directly with the DALI lighting system. There can be a need for power (e.g., a mains bus) for powering lights, air conditioning, or other high loads that are controlled by the DALI lighting system, a digital control circuit (e.g., that interfaces with the DALI lighting system) to be able to communicate with the central controller device of the DALI lighting system and controls the relays, and/or additional power to be supplied from the mains bus for powering the control circuit. The additional power may be needed because switching high loads from a low power digital bus can require expensive high current relays with an alternating current mains bus providing the power to the relays or two or more relay stages that can be expensive and complicated or impossible in some cases.